Such devices have been known for a long time and for a wide variety of uses and applications, in particular on machinery or equipment. Generically, they consist of a usually circular crown, from which gripping and manoeuvring means depart, possibly provided with a handle.
Depending on various requirements, the devices on the market may have or not, elements for halting the rotation of the manoeuvring shaft.
For the displacement of the moving body on which the manoeuvring element is mounted to occur only in conditions of maximum safety, and only by authorised operators, pressure-activated safety means which may be controlled from the outside are provided, to engage—when activated—the structure on which the element is mounted and prevent the rotation thereof. At the moment, such means consist of an axially moving, outwardly protruding plunger carrying internally at least a protruding pin and, in the structure on which the element is mounted, a plurality of holes apt to receive said pins.
If required, the manoeuvring element is provided with a lock of the axial movements thereof, for example in case one wants to avoid tampering or displacement errors.
As is understandable from the above-reported description, the safety means are structured so that—upon the actuation of the manoeuvring element—they protrude from the manoeuvring element, risking to cause logistics problems, since this type of devices is often provided in cramped spaces, where also a small bulk takes up significant importance.